The invention is directed to method and apparatus for a centrifugal pump and more particularly a high speed centrifugal pump. In high speed pump applications it has always been difficult to properly arrange the bearings that are used to support the shaft upon which the impeller is mounted. In most applications at least two sets of bearings are used to support the shaft and to accomodate the loads that are placed on the shaft by the drive means for the pump.
Frequently, the bearings are sealed in a special chamber and a particular lubricant such as oil is used to lubricate the bearings. The special lubricant is necessary to allow the bearings to effectively handle the loads placed on the shaft. However, it is necessary to seal the bearings in a manner where the lubricant does not leak into the pumping area and contaminate the fluid that is being pumped. Obviously, this is a complex and expensive way to provide support for the rotating impeller. Also, it is frequently difficult to detect leaks of the lubricant from the bearings until too late and a large quantity of the pumped fluid has been contaminated. It is also important that the pumped fluid not contaminate the lubricant as this can decrease the effectiveness of the lubricant and result in premature failure of the bearing.
In such a high speed pump there is usually an imbalance in the pressure exerted by the pumped fluid on the rotating impeller. At the inlet for the fluid the pressure is very low and usually the pressure from the pump fluid on the opposite side of the impeller is quite high. This creates a pressure imbalance on the impeller that can effect the operation of the high speed pump.
Accordingly, it would be desirable to have a high speed pump with a simplified arrangement for the bearings that support the shaft for the impeller. In particular, it would be preferable to utilize a single bearing that is lubricated in a manner that can not contaminate the fluid that is being pump. Also, it would be desirable to have an arrangement for the impeller that balances the force on the impeller to allow the pump to operate as efficiently as possible.